Safety device for elevators



Oct. 8, 194 6. 'J DUNLOPEI'AL 2,408,761

' SAFETY DEVICE FOR ELEVATORS Filed Dec. 6, 1943 7 Sheets-Sheet 1 WITNESSES: INVENTOR5 ORNEY 7 Sheets-Sheet 2 J. DUNLOP ETAL SAFETY DEVICE FOR ELEVATORS Filed Dec.

WiTNESSES: Q Z

Oct. 8, 1946. J. DUNLOP ETAL I ,4 ,76

- I SAFETY DEVICE FOR ELEVATORS Filed Dec. 6, 1943 '7 Sh eets-Sh eet 3 I WITNESS-ES:

I INVENTORS I! mes Dun/0,0 and Oct. 8, 1946. Y J. DUNLOP ETA; 2,408,761

SAFETY'DEVICE FOR ELEVATORS Filed Dec. 6, 1943 7 Sheets-Sheet 4 WITNESSES: lNvgN'ToRs d d r fame: Dun lop an 6 I Hans E fiaflfiefl'.

Oct. 8, 1946. J. .DUNLOP ETAL 2,403,761

SAFETY DEVICE FOB. ELEVATORS Filed Dec. 6, 1943 7 Sheets-Sheet 'r Patented Oct. 8, 1946 2,408,761 f H l SAF TYI JEvI E Fonii EvA'roRs James Dunlo'p, 'RidgewoodyN. J.', -and Hans" E.

Ha'nsen, Westerligh, Staten Island, N..Y., assignors, by mesne assignments, to Westinghouse Electric Corporation,

East Pittsburgh.

' Pa., a corporation ,of Pennsylvania I 7 e, 1943; Serial No. 513,030

Application December I 211Claims. c1.'1s7- '-ss) p 1 r Our invention relates to safety devices for elevators and, more particularly,1to friction safety devices for largedeck-edge elevators on ships, or. for. drawbridges or heavy freight elevators. One fobject of' our invention is to provide a safety apparatus for an elevator body with two sets or hoistingcables which will provide means for stopping both :ends of the elevator body in eitherthe up or the down direction when either set of cableslb'reaks. r v

v.An'other object is to provide a friction safety apparatusfor eachend of'an elevator platform having two sets of hoisting cables in which the frictionalresistancetothe falling end of the platform in. case ofa break in the cables will be different from the frictional resistance in the safety apparatus at the other end of theplatform if it moves upwardly.

A further object is toprovide a safety device for an elevator having safety pawls on the elevator platform for engaging notches in the elevator guide and forpositioning the pawls at a pitch which-is a multiple of the pitch of the notches on: the elevator guides so as to reduce-the distance of free fall of-the elevator platform in case of a break inits cables. Ai'still further object is to provide a pawl and notch 'operated safety device for an elevator body havinga set ofhoisting cables at each end in which'all of the pawls will be operated'at the same" instant to stop the elevator body regardless of-which setof cables fails. v .Astill further object is to provide a safety apparatus "for an elevator platform-having a set-of hoisting cables at each end attached to hitch boxe having hitch plates for operating the safety apparatus. and in which box springs are compressed by the tension of thecables to store energy for shooting the hitch plates out of safe position into safety operating position when the safety is operated by the failure of one or both sets of cables A further object is to provide for exceptionally large elevato'r'bodies whichshall be rugged and which will provide suflicient frictional resistance to bringsuch largebodies to a stop within avery short distance without damaging either theelevator bodies or the apparatus or structures associated with it. I

it is alsolan object of our inventionto provide 'a'safety apparatus a frictional safety device which-shall be simple and easy to manufacture, install, and maintain in operation. M

. -B,e fe rence may had toethe accompanying drawings for a better understanding of the invention.

Figure 1 is a diagrammatic representation in aft end elevation of a deck-edge elevator attached to-an' outboard portion of the hull of a ship;

Fig. 2 is a diagrammatic view of the elevator shown in Fig. 1 as taken from the interior of the ship and looking in outboard direction, for illustrating the hoisting apparatus more clearly; ,Fig'. 3 is atopplan view of the elevator platform and guide rails with our-improved safety apparatus attached thereto;

. Fig. 4-. is a View in side elevation looking in the outboard direction of the elevator platform, parts of its hoisting cables, and our improved safety apparatusassociated therewith; Fig. 5 isan enlarged view in aft end elevation of .our improved safety apparatus shown in Fig. 3 mounted'on the aft end of the elevator;

. Fig. 6 is an enlarged view in side elevation Fig.10 is a view taken on the line X-X of Fig;

9 as seen when looking aft at the safety shown in :Fig. 5, and.

' Fig. 11 is a view in end elewation of a portion of theupper end of the'safety devices showing how? its outer plate is bolted to its support.

' Our invention is illustrated in connection with adeck-edge elevator such as is used on airplane carrier ships. for transferring airplanes from the main deck to the flight deck or from the flight deck toithe main deck. 'Elevators of this type have their platforms mounted on the outside of the hull at one side of the ship in alignment with an opening therein to the maindeck and are movable up and down on the side of the ship to serve the main deck and the flight deck. Some of these platforms are approximately sixtyfeetlong and extend outwardly from the hull over thirty feet. However, it is to be'understood that the invention may be used in connection with many other-forms of; elevators, drawbridges, etc.

1 Referring more particularly to Figs. 1 and 2 of the drawings, we have illustrated a deck-edge elevator comprising an elevator platform l disposed between a pair of guide rails H and I2 mounted on the outside of a ship hull l3, in position to be supported by and to be raised and lowered between a main deck l4 and a flight deck [5 by a plurality of hoistingcables l5 and I1 operated-by a hoisting engine l8.

The platform Ill comprises a base section and a hinged or outboard section 2| which nor-1:

mally lie in the sam plane and provide a large level area upon which airplanes may be moved" and carried from one deck to the other. The

sheave 50' mounted on the ship frame inside the 7131111, and thence downwardly and under a debase section of the platform is constructed .with.

a suitable flooring 22 laid upon a frame 23 made. of seamless steel tubing, structural steelseotionsand steel plate welded together in bridge like" construction to form a relatively light butstrong body. The outboard section of the platform is also constructed with a suitable floor 24' laid'upon a frame 25 of seamless steel tubing, structural steel and. steel vplate welded together in bridge-1 like construction in the same manner as the base and. is mounted upon and connected to the, base with .aJsuitable hinged joint .26 so that it may .be raised from itsnormal horizontal position into a vertical position on the base when the ship has to passv through a lock orother narrow opening.

, Thezguide rails H and 52 are mounted in .position and facing each other on the side of theship hull [-3 by means of a plurality of horizontally disposed brackets .28.

The guide rails are provided Withvertical slots 29 in their sides facing each other forreceiving aplurality of rollers .35 rotatably mounted on the base section 26 for the purpose of guiding the movement of the-elevator platform as it is raised or lowered and for also maintaining the platform in its horizontal position.v A block 3.2,is securely fastened by welding to the lower endofeach guide rail to prevent the elevator from dropping on down through the slots incase of failure of the safetiescables, etc. Normally the platform is suspended entirely by the hoisting cables. The guide rails are. also providedwith notchedv sides 33;so;that they may be used as safety standards.

in cooperation with safety, apparatus for stopping the platform in case of failure of the hoisting cables.

The hoisting engine 13 is, ahydraulic engine comprising a single cylinder txmountedin -.a horizontal position on a frame or engine bed 35 and a power plunger 33 disposed in the cylinder. The outer end of the plunger is provided with a power head 31 in which a pairof power sheaves 38 are rotatably mounted. The plungeris. designed to slide back and forth in the cylinder, and thereby move the'power sheaves to operate. the hoisting cables. Any suitablehydraulicmedium such as oil placed under pressure by anysuitable pumping apparatus (not-shown) may. be. used for operating the plunger. VA valve .49. and a motor 4| foroperatingit are mounted on the cylinder for controlling the operation of the plunger by controlling the admission of the oil to the cylinder.

The hoistingcables I6 .are secured to the aft .1 01 of the platform (Fig. 2) by suitable hitches 42 mounted thereon and pass upwardly and over an idler sheave 43 fastened to the ship structure underneath the overhanging portion of the flight deck, thence rearwardly over; a second idler sheave 44' mounted on the ship frame inside the hull, thence downwardly and under a deflector sheave 45 mounted on the engine bed- 35, thence around astationar'y sheave '46 mounted on the ilectorysheaye 51- mounted on the fore end of theengine bed,.th,ence under and over one of the power sheaves 38in the plunger head, and thence tosuitable" dead-end hitches 52 secured to the upper rear part of the engine.

' Inasmuch as the platform I0 is very long and heavyand is operated and supported entirely between its guide rails by the hoisting cables at its fore andaft ends, anample safety means for stoppingit quickly and safely andrestin it upon its guide rails,,upon failureof the hoisting. cables at eithe-ror both ends of the platform .isrequired. Furthermore, inasmuch, as the platform isoperated by two sets ofcables,one at. each. end, a safety means for both up and down direction is required, so that if the cables atone end break and the cables at the, other end continue their upward pull, the platform will, be stopped at both ends before it tilts to a dangerous position.

Also, in case of failure of the cables atonly'one end while the platform is moving. upwardlythe downward pull of gravity atthatend. and the upward pull of the intact-cables at the other end will require the applicationsof different frictional stopping. forces for .the up direction and the down direction to keep the platform from being stopped in a tilted condition;

In order to meet these requirements, we have provided the platform with safeties 53 and 54 having stopping pawls biasedgto engage notches 33 on'the guide rails or safety standardsto'stop the platform upon failure of either .or both sets of cables. The pawls on both-safeties are re.- strained from operation by; ,a pair of, gates controlled through an operating rod 55 biased towards pawl releasing position by a compression spring 56 in a casing 5'! but prevented from moving to-itspawl releasing position by tri gerv hitch plates-g58 and 59 on the platform ends of the cables. Furthermore, f rtictionplatesare mounted in the safeties to permit, alimited relative movement between-the safeties and the platform when the safetiesgrab the guide rails for either direction.

.If..either .set of cables fails, its trigger; hitch plate releases the rod to. operation by the biasing spring which causes the rod to release the pawls onboth safeties so that they dig into the notched guide rails and thereby stop the safeties and the platform, the friction plates absorbing suchdamaging energy as may be generated by the sudden stopping of the platform by the safeties.

Referring more particularly to l 'igs. 6, 8, 9, 10 and 1 1', the safety 53 comprises a pawl carriage orsafet y device 64'connected by frictional devices with a housing 5i having a rear housing plate 62 and a front housin plate 63 mounted on the platform. The rear housing plate 62 is provided with an inwardly. extending friction fin or plate 65, and is mounted in a vertical position between an upper beam 65 and a lower beam 61 constructed of steel plates. Each beam is welded securelyto the frame 23 of the base section plat- 7 low endto. theglower, beam 81 by form; iThe I rear.;housing; plate; .62 is welded; to the-peamsiso 'as; toprovide' a strong permanent attachment tothe platform; frame .suflicient to withstand any strain which may be placed upon the safety. The fronthousing plate 63 is provided with an inwardly extending friction fin or plate 68Zf'acingzthe fin 65 on the rear plate and 1S $8f cured at its upper end to the beam 56: and at; its a plurality of bolts and plates :59. so as to facilitate the assem+ bling .or removal of the pawl carriage and the parts associated with.v it; 1 The housing plates should be made of stainless steel so that their coeflicient of friction will remain, constantbefore and-afterthe safety has :be'enin salt water spray. 1'1' Th -p wl, c r 4 sa lon hann 1..lik stainless steel block disposed, in a recess .10 formed by the outer left-hand edges of the housing plates and their friction fins (Figs 9,). It is-shcrter than theghousing plates and they may slide up or down on% it in case of a safety stop. Three up pointing .pawls II, I2 and I3 and three down pointing pawls 114', I5, and I6 are mounted in'the carriage body for engaging safety standards such as the notched portions33 of. the guide rail to stop the pawl carriage when the cables fail.

The base of the down pointing pawl I6 is rotatably-seated in a socket ll in the carriage body and, is retained in that position by a loose hinge pin Ila. g p I Acompressionspring 88 is provided for biasing the pawl 18 to project outwardly. The spring 88 1s concentrically mounted on a rod 8| having itsinner; end pivotally. attached to the pawl 18 by a pivot pin 82 and iscompressed between a shoulder 83 on the lower end of the rod 8I and a spanner nut 84 mounted on the ,outer end of a tube 85; the inner end of which is seated in and welded to the pawl carriage 84. Eachpawl is provided with a finger projection I8 at its one side to'be engaged by a holding gate I97 controlled by theoperating rod lit so that operation of the rod will open the gate to release thepawls to engage the notches 68 in the guide rails upon failure of one orboth-sets of cables. 1 .1 i A temporary nut 86 is illustrated as mounted on the screw threaded end oftherod 8| for holding the paw1,,'l6 within itsrecess until thegate :19 is closedto hold thepawl. After the resetting operation of closing movedand thegate holds the pawl against the efiectof the biasing spring 88. .Eachof the pawls is provided with a similar'biasing spring. ,The .pawl carriage 84. is shorter than therejce'ss formed by;the. housing plates in which it-isdisposed so that it may move longitudinally a limited distance thereineither direction when the safety is set to stop the platform. v 37 r I ,In order to provide-apredetermined frictional resistanceto the movementof the carriage in the housingplates, a strip of brake lining 88 is fastened to the carriage 64 in, position to engage the adjacent face of the friction fin 65 andla strip .of brake lining 89is fastened to the, carriage body in position to engage the adjacent face of the friction 111188. A friction plate 98 is disposed at, the other sides of the fins 65 and 68 and is loosely mounted upon a plurality of short, round tubular projections BI mounted in the central innergface ofgthegpawl carriage and welded thereto. to makea solidconnection therewith so that vertical movement of the carriage will carry the vfriction pl teSI) withit. The frictionplate 90 is also providedwith holes whichper-mit it to fit over th b la i r e ta l the gate, the nut 86 is re- I 6 A. strip ofbrake lining 92 is mounted on the friction" plate 90 in position to engage the-adjacent face of the friction fin 68 (Fig. 9) anda similar strip 9310f brake lining ,is 'disposedon the opposite side of thefriction plate toengage a ,long friction bar 94v embraced between that brake. lining and a strip of brake ,,1ining;;95 mounted on a friction strip 96. A strip of brake lining 91 is fixed on the'friction plate ,98. iniposition to engage the adjacent face of the friction fin 65 and ,a-strip of brake lining 98 is fixed on the opposite side of the friction plate 98in po sition to engage a."short friction bar 99 dis-- posed between that strip of brake lining and, a strip of brake lininglIlI'I fastened to the, friction strip 96. The lower ends of the barsg94'andr99 sit on the bottom plate IOI resting ,on and Welded tothebeam Bl. I 'Thefriction strip 96 .is loosely mounted upon the tubular members 85 so that itas wellas the frictionplate 98 will remain with the pawlfcarriage when: the pawl carriage is stopped by the safety pawls and the continued motion of the 7 platform moves the housing plates up or down on the carriage. This arrangement of the pawl carriage, the friction-fins plate, bars and strip with the brake lining strips-disposed therebetween provides a frictional resistance to brakethe movement of the housing stripson the pawl carriage when .it. grips the guide rails ,for absorbing the shock of suddenly stoppingthe platform-byithe setting of the safety pawls. s

A plurality of heavy friction springs are pro, vided for pressing the friction plates, rods, fins, and the carriage body tightly together to increase their friotional resistance to a'predetermined amount sufficient to bring the platform to rest within a predetermined distance after the safety pawls set on the guide rails. The heavy friction springs associated withthe pawl 16. bear I the reference; characters I86 and I811 and are concentrically mounted on the tubular support between the outer face of the friction strip 98 and a round shoulder plate I88 mounted on;the

- outer end of the tubular support 85 and held in position thereon by the spanner nut 84. V Y

A look washer I89 and a lock washer base ,I III are mounted between the spanner nut and the shoulder plate I08 to prevent the spanner nut from getting loose after it is tightened on itsfric tion spring, The lock washer base is provided witha pin I I I which extends into a depression in the shoulder plate and the lock washer is pro vided wit-ha serrated edge, one of the projections I12 of whichis bent downwardly into a depression in the lock support and another projection I I3 of which isbent upwardly into a notch inthe spanning nut after the spanrnngnut is. tightened ag i ns the shoulder plate I118; The compression springs I06 and IIlI are very; strongandjitji s usual to use a lever arrangementfor turning the spanner nut 84 down against thesprings to com press them sufficiently against the friction strip 96. Similar compression springs are mountedin a similar manner opposite each pawl. The compression springs are so designed that they cover practically the whole area of the compression strip. Hence the pressure on the brake linings willibe very evenly distributed. 7 The holding gate I9 (Fig. 6) is a rectangular framework constructed of seamless steel tubing II5 welded together with its rear. end pivotally mounted at the points I I6 andI I! on the safety support beams 66 and 61. The front edge tube J1 [o th gate a We ded ref af e e sele facingstrip II:9 (Fig. 9) which bears. against the fingersIB on the pawlsand holds the pawls within their recesses as long as the gate is in its closed position. When. the gate is released, the pawls fly outward-1y under the force of their compression springs I06 and I into engagement with the notches 33 in the guide rails to stop the safety.

- The down pawls in thedrawings are located a distance apart approximately equal to one and two-thirds of the pitch of the notches- 33 in the guide rail so that the setting of the pawls against the notches will stop the safety instantly or at the most, where the pitch of the notches is, say, six inches, within a two inch travel of the safety along the rail after failure of one or both sets of cables. The up pawls are also shown in the drawings as located a distance apart equal to one and two-thirds of the pitch of the notches 33 in the guide rail so that the setting of the up pawls against the notches will stop the safety instantly or at the most within a two inch up travel of the safety along the rail after .cable failure. In other words, the pawls are fractionally spaced apart with respect to the pitch of the notches to permit only a fractionalpitch of free fall regardless of when the safety sets.

The means'for holding the gate I9 in its closed position to prevent operation of the pawls while the cables remain intact comprises (Fig. a holding rod I20 having its one end pivotally connected to the gate and its other end pivotally connected to the outer end of a lever arm I2! fixed on the operating rod 55. When the operatingrod is rotated to cause operation of the safeties, the arm moves the rod I20 axially to the right and thereby moves the gate away from the fingers on the pawls, thus-releasing the pawls. .The operating rod 55 is a long rotatable shaft extending the full length of the platform and supported in a plurality of bearings I22 on the platform. The rod is made up of a plurality of sections with spline points at every bearing securing it to the platform so that it may be rotated freely and easily in the event of failure of the cables without any trouble due to warping or weaving of the platform frame 23,

The safety '54 at the fore end of the platform is constructed ls the same manner as the safety 53 at the aft end of the platform and its gate I24 is connected by a rod I25 and a lever arm I25 to the operating rod 55 in the same manner as the gate 53 is connected thereto so-that operation of the rod '55 at any time will effect simultaneous operation of the pawl freeing gates on both safeties 53 and 54.

Thecasing 51 for the'biasing spring 56 is mounted on the central portion of the frame 23 adjacent to the center portion of the operating rod 55. The spring 56 is mounted between the bottom of the casing 51 and a push rod I21, the outer end of which extends out of the casing and is pivotally connected by a hinge joint I 28 to the outer end of a lever arm I23 fixed on the-operating rod 55 sothat the'spring 56 tends to rotate the rod 55 to open the pawl gates and release the pawls into the notches in the guide rails.

The means for restraining the rod against rotation by the biasing spring 56 comprises a safety cable I3I extending the full length of the platform with its ends connected by triggers I35 and I'35a with the trigger plates and itscentral portion is threadedthrough a thimble device--I 3-2 on the outer end of the arm I29 opposite the spring push rod I21. The aft end of the safety cable is threaded through an eyelet bearing. I33 in the frame 23, over a slide-bearing I34 onthe frame and down to the rear end of the trigger I35pivotally mounted in a bearing I36 on the underside of the cable hitch bracket 42a. The frontendof the trigger I 35 isprovided with a trigger face resting on a trigger point I31 welded to the trigger plate 58. a

The trigger plate 58 rests loosely against the lower face of the cable hitch box I 39 which is constructed of a plurality of metal plates welded together and to the hitch bracket in a box-like construction. Each of thecables I6 is pivotally connected by a socket I40 to the upper end of a hitch rod I4I, the lower end of which passes through the-hit'ch-box I39 and the trigger .plate 58 and issecured in that position by a plurality of nuts I42. 7

A compression spring I43 is mounted on each hitch rod and is compressed between the inner face of the topplate on the hitch box and the upper face of the trigger plate. When the cables and the trigger plate are installed, the nuts I42 are turned to draw the hitch rods to the point where the trigger plate engages the underside of the hitch box and thereby compresses the springs I 43 until the trigger plate provides a'dead end hitch for the cables and the springs store up suflicient energy to'throw the-trigger plate downwardly upon failure of the cables. It will be obvious that the springs I43 should be of such size that they will be strong enough to kick out the trigger plate 58 upon failure of the cables but will not be strong enough to raise the hitch box above the trigger plate.

The fore end of the safety cable (Fig. 3) extendsthrough an eyelet bearing I45in the frame '23 and then down over a slide shoe I46 to the rear end of the trigger I35amounted on the bracket for the cable hitch'48 in association with the trigger plate 59 as its aft end is connected with thetrigger and trigger plate at the cable hitch 42. 7

With thisarrangement of the safety cable, the failure of either set of cables-will release its trigger plate which, in turn, will release its trigger and thereby release the safety cable to release the arm I29 of therotating rod 55 and thereby permitthatrod to turn in its bearings under the biasing operation of the spring 56 and thus move the crank arms I21 and 126 to operate their rods I211 and I25 to open the gates 19 and I-24 at the ends of the platform, thus releasing all of the pawls simultaneously onboth of the safeties 53 and 54't0 stop the safeties on the notched guide rails.

A slipper or bumper block I48- (Fig. 11) is mounted in the outer end of eachof the beam supports-63 and 61 in position to engage a plate at theside of the guide rail when the platform may be moved end-ways an excessive distance under excessive wave shock.

As illustrated in- Fig. 10, a resetting and holding bolt I is mounted in vertical position in the uppersupport beam 66 to pass down through that beam and through the upper end of the pawl carriage 64. The bolt is provided with suitable nuts by means of which the pawl carriage 64 may be reset to its correct position in approximately the center of the safety housing after it'has been moved-downwardly under the-impact'of a safety operation and also acts as an initial resistance to up movement of the platform on the carriage during a safety stop. The bolt I50- has a cut away portion I5Ila to a small diameter to insure device between a plurality'of-'railswith the in'- tention' of keeping the platform level-j when it omes to rest. s In a-deck-'edge elevatorthe platform is so large, sometimes sixty feet wide, that distortion is almost;inevitable;- also long and over thirty feet rotation of the operating I x I U rod movesits leverarms- I2I andIZ B in clockwise direction (Figs. '3, Land t 53 -;siinultaneously to operate theirr rods I and the unequal positioning of load iseiipeoted and allowable. Therefore, the present safety is 'designed to permit the platform to stop atia pre determined maximum: amount out of leveL-governed by the spacing orthe distance'between the notches for the'pawls, thestaggering of the: pawls in relation thereto onthe sides of rails andthe housing a dead stop: when it has passed through its maximum cushioning space between the car-- riage and the ends of the housing GI;- The'ele: vator in battleaction will'be able town on only onecable on each'side of platform should the other'cables be shot away;-- The safeties will 'be setaonlywhen all the cables? on onesideor the other fail, and the safetiesforiboth rails will be set when allthe'cables oneithenside fails: U Assumed; operation of the apparatus I It will'be assumed that the safety apparatus has been placed in condition for operation; that is, all the compression springs I06 and I!!'I ,-h ave been compressed against the friction'strip 96 by rotate ingthe spanner nuts 84 to the necessary degree; that the pawl restraining'gates 19 and IZA-haVe been pulled up against the restrainin fmge-rs' '18 on the p w and are he d n h O ii n byreason of the fact that-the -triggers I3 and 1 35a shave been placed "behind the trigger points I31 on the trigger plates 58 and 59; and that "all of the temporary nuts 86 onthepawl-aods 18L have been removed to permit the pawlsprings I to push the gates I9 and I M-open simultaneously thus releasing the pawls -into.fengage;

ment with the notches in the guide rails; E

The outward movement of the gate. I9 moves'its outeredge II9=away from the pawlfingers'Iil on the'safety -53, thereby releasing the pawls' to the efiectof their'b-iasing springs 80. In considering Fig, 5, it willbe assumed thatlthe down pawl .16, projectsinto the notch-shoulderfiiia and thereby stops the pawl carriage 64 onjthe guide rails} Q,

'asmuch as the elevator platform ,HJ, weighs many tons, its down movement will suddenly throw; an enormous load :upon :the carriage,;-but

the frictional resistance betweenthe'fins,on the housing and long rodsheldby the housinglplates and th friction plate and. striprheldbythe car riagedue to the -brake linings mounted between them will cushion the, down movement of, ,the platform and housing against the. stoppedtcarriagesufliciently to bring the aft'end of the elevator platform to rest on the pawl carriagewithout doing any damage to the elevator structures It should be noted that the short friction: rod is not effective inthisoperation. Thisoccurs-be cause the short-friction rod,doesnotextelnd to the upper end-of thehousing and, therefore,--is not moved downwardly between ,the adjacent brakelinings; 1 "1 7 q Inasmuch-.asthe gates I24 for the ;safety; 54' was opened simultaneously with thegate is on the safety 53, .the pawl carriage-on the-safety '54 will be operated simultaneously to grip the guide: rail I2 and bring the fore end of-ltheelevator to:

rest in. the 'same manner as the aft end was brought torestq 5 :If bothsets of cables breakat the same time; while the platform is being lowered, the safeties I will be'operated in-the same manner.

to bias -the-pawls outwardly against'their re straining gates. we It will be assumed now that the elevatorplatform has been loadedand is being moved from its upper deck toits lower, deck by the,. usualopera'-V 'tion of the hoisting'engine I8 to lowerthe plat-- form.., '-'I It will be assumed further that-the cables Ifi fail by'reason of being; shot away or suddenly breaking and therebyvpernrit themlatform to fall unless the safety apparatus operates to stop it an'd'supportit'on theguide'rails; .7

"The; complete failure: of the hoisting; cables I 6 permits the. stored up energy in the trigger springs 143 Figifi) to shoot. the trigger plateSBaWay .fror'nithe .hitch base. I39 and thereby release the trigger. I 35 .toeffect the release of the. stopping pawls-landacause the platform-:toT-be stopped and brought to rests-on the guide rails; g

- T'he' release ,of the trigger .I 35- causes its rear arm: to-flyiupwardlyunderi the tension in the It willbe' assumed-now that the hoistin see I5 are repaired and that the housing engine is operated to raise;, the platform slightly ;to release: the pawls fromthe notches-in the-guide rails Flrst'the spanner nuts 84 are loosenedpto free the friction plates sorthatthe carriage canbe restored to itscontrollocation at approximately the center of the recess. in in which it is disposed, where it will be in its correct position for the next safety operation. Next the temporary nuts '86 are placed on the pawl rods 8 I and tightened to pull the. pawlsjwithin their recesses After the pawlsare pulled in, the carriage is moved to its central position and the spanner nutsgare tightenedr Next" the gates "IB and I24 are reclosed against lithe-restraining fingers "I8 I on thfi pawn and the ,safety ro pe' I;3I is 'again adiustedyrithe triggers I35 and- I35a so as-to return the biasing spring 56" to its 1 compressed biasing. position in,

I turned to their,pawlrestrainingpositionsand-are held; in suchpositions .bythe safety rope Isl -fastened to the tr ggers, which are inrturn held by Salfctyrope J3! and thereby release thQitension rose rom; ho th e in rod-am I29 ga st the ,pres-sureexerted bythe biasingspring il ngthe as ns fl- .ZUP :b ngf ea the i sinss rin ingi tfi iae n 0 27' F 1 fillillt lifllrpge nst h O erat n Qro 29 ro a es nh t min-ooap d n FT j thetrigger plates 58 and e It will-begassumed t been in operation for some timeland that while 59 the temporary. nuts 88 are removedand the safety is ready for operatiomagainwhen needed t v- I .ow that the elevator. has

it is bein e movedlupwardly fro the ,loWer gear to the flight f deck,

fore, end of the eleff'ator are sho-t.away and that thatend of the platform starts to .'fall. Meanwhile jthe' hoistingiengine ,is raising' the a end Qf the. eleyator platform 'through the {cables its hoisting? cables. I! orjr' ithe 11 When the fore endof the'platform started to'fall, the broken cables I1 permitted the triggerplate 59 to move downwardly under its energy storing springs and: thus released the trigger i35ia to release the safety cable l3l". The release of the cable l3! releases the biasing spring 55" so that it rotates the operating rod' 55 as described in the previous safety operation, and it, in turn, simul-' taneously opens both gates l9 an'd I24. The release of the gate l 24 sets the-pawl carriage of the safety 54 to be stopped: by its down pawls engagingqthe notched guide rail 12 and the fore endof the platform is brought to rest on the pawl carriage in the same manner as in the previously described operation. 1

However, in this accident the hoisting engine is raising the platform and the intact cables Hi continue to exert an upward force on the aft end of the platform tending to tilt thepla'tform dangerously. Thistilting tendencyisquickly stopped because the pawls of the safety-53- are released to engage the notched guide rail H. In this instance it wi-llbe assumed that the uppawl la' engages the notched shoulder 336 and thereby stops any further upward movement of its pawl carriage; Inasmuch as the pawl carriage is now prevented from moving upwardly any further, the aft end of the platform will be stopped from any further upward movement and the energy in volvedin this stopping'eifect will be absorbed by the failure of the bolt l5!) and by the frictional resistance between the plates carried by the pawl carriage and the fins carried'by the housing plates as Well as by the long friction rod and the short friction rod mounted to rest on the bottom of the'housin-g.

Inasmuch as the short friction rod is effectively used in this operation, the total frictional resistance is greater than the frictional resistance effective in a down stop. This increased frictional resistance in an up safety stop is sufficient to take care of the up pull exerted by the hoisting engine on the; cables l6 so that the platform is stoppedwithout becoming dangerously tilted up Wardly at the end to which the intact cables are attached-'. t It will be assumed now that the cables" are repaired and that the safety'apparatus is restored I to its normal condition for thelnext safety action in the same manner as described in the previous assumed actions.

By the foregoing description it will be seen that wehave provided an improved safety apparatus for elevators which is particularly useful in connectionwith extremely large and Ionghoistable bodies such-as airplaneelevator platforms, draw bridges, extremely heavy freightelevatorsfetc. It will also be observed that the safety apparatus will stopthe platform when either one or both sets of cables fail during down travel of the plat form, or when both sets of cables fail during up travel, and that it will's'top one end of the platform when it starts to fall during up operation and the other end of the platform if it starts to tilt upwardly under the up pull of the cables on thatend. y g

Furthermore, if the safety is used on aneleyator having a set of hoisting cablesat each end, the safety will operate simultaneously at both ends foreither direction of travel regardless of whether either one of the sets of cables breaks or both sets of the cables break. It'will also be observed that the safety will provide differentde grees of stopping friction for the up and the down direction to take care of the difi'erenjce in force exerted by the platform being pulled up at one end and the force exerted by the down fallingend. Although we have illustrated and'described' only one embodiment of our invention, it is to beunderstood that changes therein and modifications thereof may be made without departing from the spirit and scope of the invention.

We claim as our invention:

1. In an elevator, a platform, a hoisting means for each end of the platform, an eng'ine'for operating the hoisting means to raise or lower'the platform, a pair of guide rails for guidingthe platform, each of said guide rails being provided with a notched surface, a safety device for each end of the platform-adjacent to the guide rails,

a frictional means connecting each safety device to its end of the platform to permit ifricti'onally resisted movement of the platform onthe safety device, means mounted with. said frictional means for providing greater frictional" resistance to an up safety stop of the platform than to a down safety stop of the platform, a plurality or: up safety pawls mounted in each of" said safety devices in position for engaging it's notched guide rail, said up pawls'being fractionally spaced apart with respect to the pitch of the notches in its guide rail, a plurality of down safety pawls mounted in each of said safety devices in position for engaging its notched guide rail, said down pawls being fractionally spaced apart with respect to the pitch of thenotches in its guide rail, resilient means for biasing said pawlsinto locking engagement with the notched portions of the guide rails, a gate associated with each of said safety devices for restraining the safety pawls thereon from engagement with the guide rail associated therewith, an operating rod connected to both of said gates, a biasing means for biasing said operating rod to move said gates to pawl releasing position, a safety cable connected to said operating rod to restrain it from moving the gates to their pawl-releasing positions, a hitch device for connecting each hoisting means to itsend of the platformj'a trigger attached to each end of the safety cable and pivotally mounted adjacent a hitch device, a trigger plate associated with each hitch device fer restraining operation of the trigger adjacent thereto and, an energy storing device mounted on eaeh hitch device andresponsive to the tension of the hoisting means attached thereto for storing energy to move the trigger plate associated with that hitch box upon failure of that hoisting means to thereby release its tri ger on the safety cable and thereby cause the set ting of the p'awls on both safety .devices in the notched portionsof the guide rails to stop the platform.

2. In an elevator; a platform, a hoisting means for each end' of thep'latform, an engine for operating the hoisting means to .raise or lower the platform, a pair of guide rails for guiding the platform, each of said 'guide'rail's being provided with a notched surface, a' safety device for each end of the platform adjacent to the'guideirails, a. frictional means connecting" each safety device to its end oftheplatform to'pemnitfrictionallly resisted movement of the platform on'the'safety jdevice, means mounted with said frictional means for providing greater, frictional resistance to an up safety stop of the platform than to a down safety stop of the platforrma plurality of'up-safe ty pawls mounted in each ofsaid safety devices in position for engaging its'notched guiderail, said 'up pawls being fractionally spaced apart with respect to the pitchof-the notches in its guide ing 13 7, rail, a plurality of down safe'ty pawls mounted in each'of said safety devices in position for engaging its notched guiderail, said down pawls being f ractionally spaced apart with respect to the pitch an ope'rating' rod connected to both of said gates,

a safetycable' connected to said operating rod to restrain it'from releasing the gates to their pawl releasing positions, a hitch device for connecting each hoistingmeans toitsend of the platform,

a trigger means connecting each end of the safety cable to a hitchdevice, an energystoring device'mounted on each hitch device and responsive to the tension of the hoisting means attached thereto for. storing energy tooperate the trigger means'associated with that'hitch box upon failure 'of'that hoisting means for releasing the safety' cable and thereby causing the setting of the pawls on both safeties in' thenotched' portions of the guide rails'to stopthe platform. 1 V '13. In an elevator, a platform, a-set ofhoisting cables'for each end of the platform, an engine for operatingthe cables to raiseor, lowertheg-platform, a pair of guide rails forguiding the platform, each of said guide rails being providedwith a notched surface, a safety device :for eachend of the platform adjacent to the guide rails, a frictional ns Connecting each Safety device to its end of the platform topermit frictionally resisted movement-of the platformon the safetydevice,-

means mounted with said frictional niearisfor providing greater frictional resistance to an up safety stop of the platform than to a down safety stopcf the platform; apluralityof up safety pawls n'iountedin each of "said safetydevices in tionqa safety "cable for restraining the operating rod from: moving the gates'to'theirpawl releasing positio'ns a hitch device'for connecting each hoistingfmeans to the platform, a trigger attached to each end of thesafety cable and piv- 'o'tally mounted adjacent a hitch device, a trigger plate associated with eachhitch device for 1'8? straining operation of the trigger adjacent thereto, and an energystoring device mounted on each hitch idevice and responsive to the tension of the 'hoistingmeans attached thereto for storing energy' to move the trigger plate associated with that hitch box upon failure; of that hoisting means, to release its: trigger on the safety cable and thereby. cause the setting of-the pawls on both safeties in thenotched portions of the guide rails toi'stop the platform. 7 i ,15; :Inan elevator, amovable platform, a hoistingmeans for each end of the platform, an engine position for engaging its notched guide rail, said,

uppawls being fractionallyspaced apart with respect to thenotches inits guide raiha'plurality of down safety pawls mounted in each of said safety devices in position for engaging its notched guide rail, said 'down pawls beingfractionally spaced apart with-respect to'the notches in its guide rail, resilient means for' biasingfsaid pawls'intolocking engagement with thenotched portions of the guide rails, and'means responsive: condition of the both sets of cables for restrainthe safety pawls from engaging the ,guide rails and responsive to failure .of' either: set of cables for releasing the pawls into'jengagement with the guide rails'for stopping the platform.- "-4. In an kalevatorQa-platform, a hoisting means foreach end of the platform, an engine-for operating the hoisting means toraise or lower the to: intact platform, a pair of guide rails forguiding the j' platform between floors, each of said guide rails being provided with a-hotched surface; a safety mounted at'each end of the platformadjacentto the guid urails, a pluralitynof. up safety pawls mountedin each of said safeties. ,a plurality offldownusafetys pawls mounted in each of said safeties, resilient means for ioiasing said pawls toward; locking engagement with the notched portions of the guide rails, a gate asso- .lment Withthe ciated with eachof said safeties for restraining I the safety pawls thereon from engagement with the guide rail associated therewith, a plurality of levers connected to said safety gates, anoperating' rod"connecte d to said levers, a biasing means for biasing said operating rod to move said levers-and said gates to paWI-reIeasingpOsifor operating the hoisting means to raise or lower the platform; a safety "element fixed adjacent to each end of theplatformasafety device mounted on each end of the-platform adjacent to the safety .elementat that: end of .the. platform, a plurality of safetypawls mountedzin saidsafeties, resilient me'ansfor biasing saidpawls toward locking engagement with the safety elements, a gate asso- 'ciated withae'ach of -said safeties for restraining thesafety: pawls thereon from-engagement; with the safety' element associated therewith, an operplatform, ,a trigger attached. to.-eachend 'ofthe safety, cable and ,hitchdevice for restraining operation, of the trig-.- ger adjacent thereto and, an energy storing deyiqe ounted on each hitch device and responsive .to the tension of the hoistingmeans attached there:

to'forstoring energy to movethe trigger plate associated "with thathitch boxupon failureiof that, hoisting meansto, release its trigger on the safety, cable and thereby cause the setting of the pawlson both safeties in the notched portions of the guide rails to stop the platform,

6. In an elevator, a movable platform, ahoisting means'for each end of the-platformanenginefor operating the .hoisting means to raise or lower the platform, a pairof guide rails for guiding the platform bet-ween floors, eachu of said .guiderails beingprovided, with a notched surface, a safety devicef fmounted at each :end of the platform ad jace'nt ,to the guide rails, a plurality ofvsafety palvils mounted in said safeties, resilient, means for biasing said pawlstoward locking engagement with the notched portions of the-guide rails, a gat,e associated with'each, of said safeties for .re-

' straining the safety ,pawls thereon from engage- I 7 guide rail associatedtherewith t n,' 'der the pressure of their biasing means, an operating rod c "cted to said gates', a biasing means for biasing d operating" rod toimove said gates to pawl-releasingposition, a safety cable'for restraining operating rod from moving the gates their pawl-releasing positions; and means re- 's'ponsive to t'h'e failure of either hoisting means forrel'ea'sing the safety cabl'e andthereby cau's- 'ing the setting of the pawls on both. safeties in I the inot'ched portions iof the 'guide .railsto, stop 7'."-In-;ah: elevator,1 a'movableplatfomma hoistpivotally mountedv adjacent -a' hitch device, a trigger plate associated with each 15 inglfmeans for each'end of the platform, an engine for'operating'the hoisting means to raise or lower the platform, a safety standard fixed adjacent to eachend of the platform, a safet mounted on each end of thev platform adjacent to the safety standard ther'eat, a plurality of up safety pawls mounted: ineach of said safeties for engaging its safety standard to prevent up movement of the platform, a plurality of down safety pawls mounted in each of said safeties, for engaging its safety standard to prevent down movement of the'platform, means for biasing said pawls tvrard'locking'engagement with the safety standards, nieansassociated with each of said safeties for restraining the safety pawls thereon from eiigagement with the safety standard associated therewith, hitch devices for connecting the hoisting-means to the platform, and trigger means associated with the hitch devices and responsive to intact condition of the hoisting means for pre venting the pawl restraining means from releasmeme pawls and responsive to failure of the hoisting'means at either end of the platform for causing the' pawlv restraining means to release the pawls intolocking engagement with the safety standards to-stop the platform in either direction.

m an elevating apparatus, a movable platv oisting' cables for the platform a safety standa d" provided with notches disposed adjacentthe platform, a safety device mounted on the platform; a plurality of up safety pawls pivotally mounted in the safety device for engaging the notches in the safety standard, said up pawls being fractionally spaced apart with respect to the pitch of the notches in the safety standard, a plurality of down safet pawls pivotally mounted in the safety device for engaging the notches in the safety standard, said down pawls being fractionally spaced apart with respect to the pitch of'the notches on the safety standard, means for biasing the pawls toward engagement with the notches in the safety standard, and means responsive to intact condition of the hoisting cables for preventing the pawls from engaging the safety standards and responsive to failure of the hoisting cables for releasing the pawls into engagementwith, the safety standard to stop the platform.

9-. In an elevator, a movable platform, a set of hoisting cables for each end of the platform, a safety standard provided with notches disposed adjacent to eachend of the platform, a safety device mounted. on each end of the platform, a

pluralityof up safety pawls pivotally mounted each safety device for engaging the notches in i s safety standard, said up pawlsbeing fractionally spaced apart with respect to the pitch of the notches in the safety standard, a plurality of down safety pawls pivotally mounted in each safety device for engaging the notches in its saffe'tyv standard, said down pawls being fractionally paced apart withrespe ct .to the notches on itss'afety standard, means for biasing the pawls toward engagement with .the notches in the safety standards, and means responsive to intact condition of both sets ofhoistingcables for pre- ;venting the pawls from engaging the safety standards and responsive to failure of either set ofrhoisting cables for releasing all the pawls into engagement with the safety standard to stop theplaltform;

10. In anelevating apparatus, a movable platform, hoisting cables for the p1atform,-a safety standardprovided v'zith notches disposed adjacent the safety element.

15 the platform, a safety device, means for mountthe safety-device on the platform, a plurality ofv up safety pawls pivotally mounted in the safety device for engaging the notches in the safety standard, said up pawls being fractionally spaced apart with respect to the notches inthe safety standard, a plurality of down safety pawls pivotally'mounted, in the safety device for engaging the'notclies inthe safety standard, said down pawlswbe'ing fractionally spaced apart with respect to the notches on the safety standard, means for biasing the pawls toward engagement with the notches in the safety standard, means responsive to intact condition? cfthe hoisting cables for preventing the pawlsfrom engaging the safety standard and responsive to failure of the h'oi'stingf'cablesifor releasing the pawls into engagementrwith the safety standard to stop'the platform, slidablefriction means disposed in the safety mounting means for providing frictionalresistance to movement 'of the platform on "the safety device when it engages the safety standard in making a safety stop of the platform.

11. In an elevator; a platform, a housing attached to the platform, a friction plate carried by the housing, a carriage, a, pawl mounted "on the carriage T1 or engaging a safety element during'a safety'stop; a friction plate carried by the carriage, an adjustable resilient means: for moun'tin'g'the carriageon the housing by hold-' ing the plates in slidable frictional engagement 'each'other, means for. limiting the relative movement of the plates, and an adjusting device mo'unted on'the housing and the carriage for returningthe carriage to its'p-redetermined normal position on the housing after it has been dislodged therefrom in a safety operation.

'12. In an elevator, a safety element, a platform movable along the .safetyelement, a, housing "attached to the'pla'tform, a friction plate carried by'the housing, a carriage, a pawl mounted on the carriage for engaging the safety element duringa safety stop, a friction plate carried by the carriage, and means for'mounting the carriage on" the housing-by holding the plates in slidable frictional'engagement with each other, to permit relative movement between the platform and the carriage when the pawl engages 13L'In an elevator; a platform, a housing attached to the platform, a'friction plate carried by the housing, a carriage, a pawl mounted on the carriage f'orengaging a safety elementduring a safety stop, africti'on'plate carried by-the carriagejan adjustable resilient means for mounting the carriage on thehousing by holding the plates inslidab'le frictional engagement with each other,'- and means for limiting the relative movement of the plates.

l4. In a safety device for an elevating means, ain'ovable platform, hoisting cables for the platform, a safety standard associated with the platdevice-from grabbing the safety standard while the ;cables are intact and for; causing the safety 1'7 device to-grab the safety standard and; stop the platform-iipon failure 'of the cables. -f 15, Hi a'saf'ety device for an elevating means, a movable platform, a set of hoisting cables for each endof the'platform,a safety standard associated with eachend of the platform, a housing mounted on each end-oflthe-platform, a'frice tion plate mounted" on'ea'ch housing, asafety device for the housing at each end of the platform for engaging thejst'andard at that end of the platform t'ostop tlie' platform, a friction plate carried by each safety device, means for frictionally attaching the safety to the friction plate on mit them to slide on each other and thereby create frictional resistance to relative movement 7 of the safety devices and the housings, means controlled by both sets of cables for preventing the safety devices from grabbing the safety standards while both sets of cables are intact and for causing both safety devices to grab the safety standards and stop the platform upon failure of either set of cables.

16. In a safety device for an elevating means, a movable platform, hoisting cables for the platform, a safety standard associated with the platform, a housing mounted on the platform, a friction plate mounted on the housing, a safety device for engaging the standard to stop the platform, a friction plate carried by the safety device, means for frictionally attaching the safety device friction plate to'the housing friction plate to permit one to slide on the other and thereby create frictional resistance to relative movement of the safety device and the housing, additional frictional means disposed in the frictional attaching means to provide greater frictional resistance t upward movement of the housing on the safety device than to downward movement of the housing on the safety device, means controlled by the cables for preventing the safety device from grabbing the safety standard while the cables are intact and for causing the safety device to grab the safety standard and stop the platform upon failure of the cables.

17. In an elevating form, hoisting cables for the. platform, a housing mounted on the platform, a safety device associated with the housing for stopping the platform upon failure of the cables, and friction means for mounting the safety in the housing, said friction means comprising, a friction plate mounted in the housing, a plurality of tubes having their inner ends fixed in the safety device, a friction plate mounted on the tubes and disposed in slidablecontact with the plate in the housing, a plurality of springs mounted on the outer ends of the tubes, and means for compressing the springs against the plates to secure a predetermined frictional resistance between the plates for braking the movement of the housing on the safety device.

18. In an elevator, a movable platform, a fixed safety element disposed adjacent to the platform, a housing attached to the platform, a long friction rod disposed in the housing with its upper end and its lower end extending approximately into engagement with the ends of the housing, a short friction rod disposed in the housing with its lower end in approximate engagement with the lower end of the housing and its upper end some distance from the upper end of the housing device, a movable platfriction plate of each its housing to per- 7 whereby it will be moved upwardly by the housing when the housing moves upwardly on the carriage but not downwardly when the housing moves downwardlyon'the carri'agepa carriage slidably disposed in the housing, a pawl mountedon the carriage for engaging a 's'afetyelementduring a safety stop, a friction plate carried by the carriage,- andmeans for mounting'the-carriage on the housing by holding the plates and rods in slidable frictional engagement with each otherfwher'eby-the frictional resistance cre'ated by-upward movement or the housing onthe' c'arriage is greater jthan the frictional resistance created by downward movement I of the housing on the carriage.

19. In a safety mechanism for an'elevator, a movableplatform, a set of hoisting cables at each end of the platform, a safety standard associated with each end of the platform, a housing mounted on each end of the platform, a frictional plate mounted on each housing, a safety device disposed at each end of the platform for engaging the standard thereat to stop the platform, a friction plate carried by each safety device, means for frictionally attaching the friction plate of each safety device to the friction plate of the housing device at its end of the platform to create frictional resistance to relative movement of the housings and the safety devices, a bolt connecting the upper end of each housing to the upper end of the safety device associated with it, said bolt having a predetermined failure value when subjected to a tension strain to prevent upward movement of the housing relative to the safety device whereby an upward movement of one end of the platform in a safety stop will be initially restrained by the predetermined strength of the bolt and after the failure of the bolt will be frictionally restrained by the action of the friction plates, and means controlled by both sets of cables for preventing the safety devices from rabbing the safety standards while the cables are intact and for causing the safety devices to grab the safety standards for stopping theplatform upon failure of either set of cables.

20. In a safety mechanism for an elevator, a movable platform, a set of hoisting cables for the platform, a safety standard associated with the platform, a housing mounted on the platform, a safety device mounted on the housing with a limited degree of movement therebetween, means controlled by the cables for preventing the safety. device from grabbing the safety standard while the cables are intact and for causing the safety device to grab the safety standard for stopping the platform upon failure of the cables, a holding means connecting the housing and the safety device, said holding means being constructed to fail when it is subjected to a predetermined strain for initially preventing movement of the housing relative to the safety device in a safety stop until the force exerted by the determined value, and frictional means disposed between the housing and the safety device for cushioning the stopping of the housing on the safety device in the event of failure of the holding means during a safety stop, whereby the housing will be first prevented from movement on the safety device by the holding means'during a safety stop and upon failure of the holding means will be frictionally restrained by the friction means. 1

21. In a safety mechanism for an elevator, a movable platform, a set of hoisting cables for each end of the platform, a safety standard associated with each end of the platform, a housing mounted on each end of the platform, a safety device associated with each housing housing reaches a pre- 7 for engaging the 19 standard thereat to stop the platform, means controlled by the cables for preventing the safety device from grabbing the safety standards while both sets of cables are intact and for causing the safety devices to grab the safety standardswhen either set of cables fails for the purpose of stopping the platform upon the failure of either set ofthe cables, frictional means of a predetermined value disposed between each housing and its safety device for cushioning the stopping of the platformon that safety device in the down direction by a downsetting of the safety deviceapandadditional frictional means: disposed between each housing and, its safety device for operating in conjunction with the first-named frictional means to provide friction of a. greater predetermined value for cushioning the stopping of the platform on that safety device in the up direction by an up setting'of the safety device.

JLAMES DUNLOP. HANS E. HANSEN. 

